Allow users to supply extensions through a new plugin architecture

Details

Description

The illustrious Eric Wittmann demoed his plugin architecture within APIMan, which allows users to contribute, among other things, UI components (!!!). A similar structure could be extremely valuable for Artificer. Things a plugin could contribute:

The architecture should allow plugins to be deployed as JARs within Wildfly. In addition, our built-in plugins should also be delivered that way, allowing users to opt-in (rather than always take the performance hit of needlessly using the Switchyard/Teiid/RTGov plugins).